1. Biological Bases of Behavior
Part Four – The Endocrine System

2. The Endocrine System
Neurons and neural communication aren’t the only way information is communicated by our bodies. Sometimes, an alternate system communication called the endocrine system, is used.
The endocrine system operates by use of specialized groups of cells called glands, which secrete chemicals, called hormones.
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3. The Endocrine System
While the neural communication is fast, to allow us to react quickly to environmental stimuli, the endocrine system is slower and represents more long-term information transfer.
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4. Hormones and Glands
Hormones foster growth and proliferation of cells, as well as growth and development of the body in general.
Hormones perform their work by interacting with receptors on the surface of target cells, or by entering the cells and interacting with specialized molecules inside them.
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5. Hormones and Glands
Hormones are similar to neurotransmitters in that they are chemicals which interact with receptors on one cell after being secreted by another, and like neurotransmitters, hormones are key aspects of internal communication; some acting as neurotransmitters when secreted by neurons.
Hormonal control is largely an unconscious process, by which the body monitors the levels of the given hormone and the activities it affects through a negative feedback loop.
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6. The Adrenal System
The adrenal glands are located above the kidneys in two parts. The first is the adrenal medulla and the second is the adrenal cortex. The adrenal glands are important for our energy levels, moods, and stress reactions.
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7. The Adrenal System
The medulla secretes two hormones: epinephrine and norepinephrine. These two chemicals are also neurotransmitters in the nervous system, and they are important for arousal and the fight-or-flight response of the autonomic nervous system.
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8. The Adrenal System
The adrenal cortex produces more than 50 hormones for various functions vital for a physiological survival and reproductive function.
Anabolic steroids, synthetic forms of male sex hormones produced by the adrenal cortex can cause hyperaggression, mood swings, and mental instability if taken in high doses.
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9. 3 The Endocrine System Endocrine Glands Pituitary Gland Thyroid Gland
Adrenal Glands
Pancreas
Ovaries/Testes
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10. The Thyroid and Pituitary Glands
The thyroid gland regulates the metabolic rate of cells by producing the hormone thyroxine.
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11. The Thyroid and Pituitary Glands
Overproduction of this hormone can lead to hyperthyroidism, which is characterized by weight loss, high blood pressure, and muscular weakness.
Too little causes hypothyroidism, associated with slow metabolism, weight gain, and sluggishness
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12. 3 The Endocrine System Endocrine Glands Pituitary Gland Thyroid Gland
Adrenal Glands
Pancreas
Ovaries/Testes
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13. The Thyroid and Pituitary Glands
The pituitary gland is sometimes called the master gland because many endocrine glands release hormones in response to hormones released by the pituitary.
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14. The Thyroid and Pituitary Glands
The pituitary, is in turn, controlled by the hypothalamus (in the forebrain) to which it is attached.
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15. The Thyroid and Pituitary Glands
The pituitary acts as a bridge between the endocrine system and the nervous system; the nervous system signals a stressful situation to the brain, and the brain stimulates the pituitary to release adrenocorticotropic hormone (ACTH), our primary stress hormone, to affect other organs, such as the adrenal glands.
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16. 3 The Endocrine System Endocrine Glands Pituitary Gland Thyroid Gland
Adrenal Glands
Pancreas
Ovaries/Testes
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17. 3 The Endocrine System Endocrine Glands Pituitary Gland Thyroid Gland
Adrenal Glands
Pancreas
Ovaries/Testes
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18. 3 The Endocrine System Endocrine Glands Pituitary Gland Thyroid Gland
Adrenal Glands
Pancreas
Ovaries/Testes
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